As OLEDs have the advantages of simple structure, rapid response speed, low power consumption, self-luminescence and the like, a display device manufactured by adoption of the OLEDs has superior display performance and wide application prospect.
In general, a structure to be packaged in an OLED device includes structures such as an anode, an electron transport layer (ETL), an organic emission layer (EML), a hole transport layer (HTL) and a cathode. When driven by certain voltage, electrons and holes are respectively injected into the ETL and the HTL from the cathode and the anode, are migrated to the EML, and meet in the EML to form excitons, and subsequently luminescent molecules are excited to emit visible light after radiation relaxation. Thus, the number of the electrons and the holes migrated to the EML determines the luminous mass of the OLED device.
In order to ensure the number of the electrons and the holes, the work function of the anode and the cathode is usually required to be the lower the better. For instance, relatively active metals such as aluminum, magnesium and calcium are adopted to manufacture the anode and the cathode. But if the OLED device has poor package effect, moisture and oxygen in the air may run through and enter an OLED package structure. As the metals such as aluminum, magnesium and calcium in the OLED main structure are relatively active and tend to react with moisture and oxygen entering the OLED, the number of the electrons and the holes can be reduced, and hence the luminescent property of the OLED device can be affected and the service life of the OLED device can be reduced. Meanwhile, moisture and oxygen will also open unsaturated bonds of polymer, so that organic materials for forming the organic EML can be subjected to accelerated aging, and hence the luminescent property of the OLED device can be further affected and the service life of the OLED device can be further reduced. Thus, the cost of the OLED can be high, so the commercial demands cannot be satisfied.